Occupational studies are conducted to identify and quantify chemical and other causes of cancer and to understand mechanisms of carcinogenesis. Etiologic investigations utilize sophisticated industrial hygiene methods to assess occupational exposures and biochemical components to elucidate mechanisms of carcinogenic action and individual susceptibility. Methodologic studies are designed to improve study techniques and to provide direction for future research. Major etiologic investigations focus on working populations exposed to benzene, other organic solvents, acrylonitrile, formaldehyde, diesel exhausts, combustion products, electromagnetic fields, pesticides, and silica. Findings linking cancer with occupational exposures included an excess of leukemia and nasopharyngeal cancer among workers exposed to formaldehyde; leukemia among Chinese workers exposed to benzene and other solvents; employment as farmers, roofer, printers and molders and casters and risk of multiple myeloma; work as mechanics, assemblers, and farm product vendors and risk of renal cell cancer; exposure to solvents, formaldehyde and radiation and mortality from salivary gland cancer; elevated risk of lung cancer among firefighters, butchers, and textile and grain workers in Turkey; and exposure to dyes, metals and PAHs and risk of pancreatic cancer. Reviews of occupational exposures and cancer focused on risks among women, new technologists for use in the future, and methodologic approaches to exposure assessment. Ongoing projects to evaluate occupational exposures include case-control studies of bladder cancer in Spain and New England, lung cancer in Russia, renal cancer in Eastern Europe, renal cell cancer in the United States, mesothelioma in the United States, non-Hodgkin's lymphoma in the United States, bladder cancer in New England, lung cancer in China, and breast cancer, endometrial, and ovarian cancer in Poland. Ongoing cohort studies of occupational groups include miners with exposure to diesel exhausts, farmers with exposure to pesticides and other agricultural chemicals, women in many occupations in Shanghai, Coast Guard marine inspectors exposed to solvents, shipyard workers exposed to asbestos, paints and welding fumes, and cohorts of industrial workers with exposure to benzene, acrylonitrile, formaldehyde, and solvents.